With that, things like getting a plumber will skyrocket in price.
I mean why should I fix your toilet if I can be at home playing video games right now? I'm going to have a roof over my head and food in my mouth either way.
Current UBI experiments don't have the experience of going 100% of the population, so there's no way to know what will happen.
It would also depend on the specifics of how UBI would be implemented. Where I live I could stop working and live off welfare, providing a minimal standard of living. Yet almost nobody chooses this way of life as people strive for higher living standards, and for many work plays a part in giving meaning to life.
If more and more jobs get automated this might become a problem though, assuming no new non-automatable jobs are created.
I really disagree that almost anyone who has built tool assistance into someone's workflow will view their workflow as simple and view the employee with contempt - actually getting to know the BS they have to put up with on a daily basis actually deepens my appreciation for what they're doing. Sure I can cherry-pick examples that make folks look bad - employees today, even millennials, are for some reason allergic to learning keyboard shortcuts and will use right-click to paste. That's somewhat on them, but more on the company for not providing training time to teach better data entry habits.
If one of these highly skilled agricultural workers was given a robot that used scent to determine which fruit trees likely had ripe fruit that needed to be harvested - I'm sure they'd appreciate it for what it is, a tool that lets them concentrate on more important things. And, if we as a society are moving into a era where automation becomes so widespread that jobs are much fewer and far between 1) we'll waste a lot more time building freemium games or whatever BS labour sink society comes up with next and 2) we should realize that taxes need to go way up on the people still employed and UBI or other social services are needed to keep us functional as a society. Having too much productivity is such an easy problem to solve - you just don't do what America is doing and let it all coagulate into the pockets of a few hundred billionaires... and then everyone gets to live a good life.